My horn relay is missing.

[Zappafan]

I've been trying to get some of the wiring issues sorted out on a 64 GMC. One of the things that doesn't work is the horn. The internals of the horn button seem to be correct. But when I look at the wiring diagrams they all show a horn relay. Did this year come with a generator or an alternator? Mine has an alternator. My horn has a green wire going to it from a plug that has a red and black wire going to it. The other wires that are branching off from it are going to the plug that plugs into the head light harness.